How do I collect an unpaid window installation invoice?
How to collect an unpaid window installation invoice
Published May 14, 2026
Short answer
Window replacement and installation involves custom-ordered products with 4-8 week lead times that cannot be returned or resold. A deposit of 40-50% at contract signing is standard and covers your material order. The balance is due at installation completion. If the final balance goes past due, call on day 3 -- window customers who have new windows installed are generally satisfied and slow-paying, not disputing. Final payments that go past 7 days usually involve a missing check or a customer who traveled.
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Connect your booksCustom windows are made-to-order to your project's exact dimensions, glazing specs, and color. They cannot be returned to the manufacturer and cannot be used on another job. Your deposit at contract signing is not negotiable -- it exists to cover the window order, which is placed immediately after the contract is signed. A 40-50% deposit on the total contract is the industry standard.
Lead times for custom windows typically run 4-8 weeks for standard residential products and up to 12 weeks for specialty glazing (impact-rated, decorative, or commercial). During this window, keep the customer updated on the delivery schedule. Customers who feel informed and in-the-loop are less likely to have payment friction at installation.
At installation completion, walk the customer through each window -- demonstrate operation, lock function, and screen installation. Note any punch-list items (a stuck sash, a missing screen) and document them with a written acknowledgment. Complete punch-list items within 48 hours and collect final payment immediately after. Do not leave the job without a commitment on the final balance.
For past-due final balances, call on day 3. Window customers are typically homeowners who are happy with the result but slow to write a check or pull up their payment portal. A call that says 'I wanted to confirm the new windows on the Dunbar house are working well, just following up on the final balance of $3,400 -- would you like to settle over the phone today?' resolves most open window invoices on the first call.
If a balance persists past 14 days, follow up with a written invoice reminder and note that you will be filing a mechanic's lien on the property if the balance is not resolved within 10 days. Window replacement is an improvement to real property and qualifies for mechanic's lien rights in most states. Most customers pay promptly at this stage.